1. Field of the Invention
The present invention relates to a vacuum-assisted integrated circuit test socket and, more particularly, to an arrangement include a socket that is capable of being held against an associated test fixture by a first vacuum force with a second vacuum used to hold a device-under-test in position within the socket.
2. Description of the Prior Art
During the manufacture of integrated circuit devices, it is necessary to test the performance of packaged device. A typical test fixture comprises a spring-controlled socket, with the packaged device placed in the socket and the spring control used to xe2x80x9clockxe2x80x9d the package in the socket during testing. Once the testing is completed, the spring is released and the device is removed. Advantageously, the same socket may be used time and again, providing a test fixture that may be used for large volumes of a particular integrated circuit package.
Although the use of a spring-controlled socket test fixture is useful for many packages, as integrated circuit speed increases (for example, 2.5 GHz and above), the parasitic inductance and capacitance associated with the conventional socket test fixture becomes intolerable. That is, the level of the parasitics begins to interfere with the test measurements. A prior art attempt at solving this problem is to use gold lead lines on the text fixture and form the test structure of a high dielectric material. While an improvement over the prior art, the best connections of the test package to this arrangement require soldering the package to the test structure. The soldering requirement thus slows down the testing process and is, in reality, not a solution for high volume testing applications.
Thus, a need remains in the art for a test fixture capable of testing devices operating at speeds of several GHz without exhibiting the high parasitic capacitance and inductance effects of the prior art arrangements.
The need remaining in the art is addressed by the present invention, which relates to a vacuum-assisted integrated circuit test socket and, more particularly, to an arrangement include a socket that is capable of being held against an associated test fixture by a first vacuum force with a second vacuum used to hold a device-under-test in position within the socket.
In accordance with the present invention, a test socket is formed to include a plurality of integral conductive elastomer contacts. The contacts may either be molded into the socket or inserted and held in place. The socket is formed to include alignment features in the form of protrusions from the bottom surface of the socket. The protrusions align with an underlying PCB test fixture to provide the necessary electrical alignment between the fixture and the socket. The bottom surface of the socket also includes a vacuum channel such that a vacuum force pulling down through the fixture will hold the socket against the fixture. A second vacuum port is included within the top surface of the socket and used to hold a device-under-test (DUT) in place against the socket.
It is an advantage of the present invention that the use of a vacuum force to hold the socket in place on the fixture eliminates the need for drill holes in the socket and metal alignment pins for attaching the socket to the fixture, where the prior art metal pins are a contributing factor to the parasitic problems discussed above. In the arrangement of the present invention, when the performance of a test socket degrades, the vacuum may be turned off and the socket quickly and easily replaced.
An additional advantage of the vacuum-controlled arrangement of the present invention is that the use of a vacuum force to hold a DUT within a test socket allows for the insertion force to be well-controlled (i.e., the vacuum force) such that each subsequently tested device is held in place with a relatively consistent force.
Other and further advantages of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.